This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This is a one-year grant from the Collins Medical Trust to study the involvement of a gene termed FXYD1 in the neuropathology of Rett syndrome (RTT). RTT is a disorder of brain development that becomes clinically evident 8-18 months after birth. Most RTT patients carry a defective gene called MECP2. This gene encodes a protein that normally "silences" other genes. Identification of these genes is important, as it may allow researchers to devise therapeutic strategies to treat the disease. Dr. Matagne's studies showed that the brains of RTT patients, and that of mice lacking MeCP2, express more of the FXYD1 gene, which encodes a protein modulating the Sodium-Potassium ATPase pump (NKA), which is important for the maintenance of normal neuronal activity. Preliminary evidence showed that behavioral, electrophysiological and neuronal morphological abnormalities displayed by animals lacking MeCP2 are ameliorated by genetically preventing the increase in FXYD1 expression in response to MeCP2 deficiency, suggesting the possibility of using FXYD1 antagonists as therapeutic agents for the cure of Rett Syndrome. This grant funds Dr. Matagne's salary for her to investigate the cellular mechanisms by which an excess of FXYD1 alters the function of NKA and, ultimately, contributes to the neuropathology of RTT.